What does high bilirubin mean and what damage?

Depending on levels. Bilirubin is a by-product of blood cell breakdown which every living-human has. Small amount is normal, but too much can be toxic to the developing brain. Level of 14 or more in preterm and 17 in fullterm baby is concerning and needs medical attention. Feed the baby--as much as possible, more feeding, faster resolution of jaundice. Consult and follow up with doc. Good luck.